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Carb to TBI Conversion

Discussion in 'TBI & EFI Conversions' started by Kilian, Oct 23, 2019.

  1. Kilian

    Kilian Full Access Member

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    Truck Year:
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    Truck Model:
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    Engine Size:
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    I acquired an 87 1/2 ton parts truck for doing an AC conversion on my 83 3/4 ton GMC, and am now wondering about the TBI setup in the parts truck.

    Are TBI setups in demand enough that it's worth trying to salvage and sell?

    Is it worth converting the 4BBL carb setup in the 83 to TBI? As there is a whole forum on this topic, what are the benefits of going with TBI compared to a carb? Both trucks have 350s, but I don't know anything about the 350 in the parts truck other than the TBI setup should be complete.

    Don't know much about TBI, so just thought I'd ask a couple of questions on the topic. Thanks for the help.
     
  2. 1987 GMC Jimmy

    1987 GMC Jimmy Automobile Hoarder

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    I think you could find a buyer for the TBI setup. It’s not a super lucrative market, but there are enough people who want TBI or have TBI systems that are so hacked up, they want a fresh start so they can keep it TBI. That being said there are more people going simpler than more complex. Either way, TBI made a big enough splash that it and the aftermarket, wet manifold EFI it inspired aren’t going anywhere anytime soon.

    As far as you converting goes, I would say if you’re not having issues, let it be, but maybe hold onto your parts if you decide not to sell. The best thing about carb/HEI is its simplicity. You absolutely cannot beat it. TBI is simple in the grand scheme, but it’s not anything like a good carb. The best thing about TBI is it’s startability, general drivability, and its more formulaic way for diagnosing and repairing issues. When it’s really cold, my carb can be a little testy but not bad. When it’s hot outside, it heat soaks and vapor locks. When it sits for a few days or a week, it can be a little stubborn. This is an unmolested factory system, mind you.

    The TBI pops off every time no matter the temperature or time sitting. The thing I like about my carb is I’ve never had issues that lingered for a long time without solving them. TBI issues develop complex issues sometimes that require a working knowledge of the wiring, how the sensors work independently and in relation to one another, and what certain symptoms of a problem generally translate to. It all depends. I know a guy with a ‘93 Suburban with around 300,000 miles. Original everything, just oil changes and tires. I’ve had a issues crop up on mine with 183,000 miles that came from POs using cheap ignition parts and damaging other parts when they fail. You just have to be a responsible owner and not skimp where it counts.
     
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  3. 85squaredC10

    85squaredC10 Junior Member

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    I did a swap from a 85 350 quadrojet carburetor to 93 350 TBI. I absolutely love it. No more starting issues...obd tells me if there are issues...better gas mileage (not much more, but noticable)..I couldnt be happier. Did it all myself as my first swap ever.....it was a hard and tedious learning experience. The donor engine was in pretty rough shape, so I needed a complete gasket rebuild and almost all sensors were replaced. But it runs great now for better part of 3 years with little, to no issues. Mostly, when I first did the swap, I did not understand that it needed a different gas tank for fuel injection. So I struggled with running the injectors dry a few times before I switched it out. But in the long run, i feel it has more on demand power and dependability all round.

    Sent from my SM-G965U1 using Tapatalk
     
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  4. Texxxan

    Texxxan Supporting Member Supporting Member

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    What changes to your stock fuel system did you do to make this all work? I am in the process of doing this swap on a 1978 C10 350 with dual tanks.
     
  5. 85squaredC10

    85squaredC10 Junior Member

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    I bought a new baffled tank....and in-tank fuel pump for a 1987 R10 with fuel injection. Used original gas lines for return style setup. In my case, I went with -6 lines mated to the 1/4" hard lines at the pump. And of course a fuel filter appropriate for the donor vehicle. For me it was a 93 G20 van. I dont have the part numbers handy, but I bought it all from Amazon.

    Sent from my SM-G965U1 using Tapatalk
     
  6. Texxxan

    Texxxan Supporting Member Supporting Member

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    Did you use a fuel tank selector valve from an 87 R10? Did it plug in to your current selector valve?
     
  7. 85squaredC10

    85squaredC10 Junior Member

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    I only have a single tank. On drivers side. I would think that as long as the line dimensions are the same, it should fit your application. Probably just reuse your current selector. But im not positive.

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  8. Texxxan

    Texxxan Supporting Member Supporting Member

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    Thank you for your help.
     
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  9. 85squaredC10

    85squaredC10 Junior Member

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    Your very welcome. Good luck on your project. I can round up psrt numbers up you need them.

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  10. Texxxan

    Texxxan Supporting Member Supporting Member

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    I have the 87 R10 tanks and fuel pump with sending units already. Im needing to buy the 87 R10 selector valve and selector switch and maybe a harness for it if my 78 C10 harness doesn't plug in to the 87 R10 selector valve.
     
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  11. seniorbear69

    seniorbear69 Junior Member

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    HI all im new hear ! i have recently purchased a 84 c20 with a 350 .im looking to convert from the rochester to a tbi set up which i hve from an 88 firebird with a 305 complet set up .dus anybody know whot willneed to be changed to make this work on my 350 any help will be gratfully receved.steve
     
  12. Texxxan

    Texxxan Supporting Member Supporting Member

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    I bought a TBI stand alone harness and computer from PFIS online. The owner was very helpful and I received them within a week of my purchase. I already have the 350 TBI from a 93 1500. This is a plug and play installation.
     
  13. Vbb199

    Vbb199 B-rate Hillbilly Customs Supporting Member

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    The correct ECM for a 350ci motor (I have 2 spare ecm's, message me if interested).

    The throttle body on the firebird is for again, a 305ci, you'll need the larger injectors for 350 cubic inches. (I have a spare 350 throttle body that needs rebuilt if you're interested in that as well)

    Contact me by pm and we can discuss if you're interested.

    The 88 firebird will likely have a 700r4 if it's automatic (assuming it is), and your 82 c20 is probably a th350 or th400 (I'd assume),

    If you're keeping the assumed 3 speed auto in your 82, then you need not worry about torque converter lockup, if your 82 by chance DOES have a 700r4 (82 is first year of them), then that part maybe get a little complicated because lockup on the 82 possibly would be achieved differently than the 88 firebird, but I recommend heading over to the 700r4 thread in automatic transmissions here on the forum for questions related to that.

    With your 82, I'm assuming you probably are running a mechanical fuel pump, which gives you the 8 psi, you'll need a stronger fuel pump (can run inline), tbi uses 9psi on the very low end, 13 or 14 at optimal performance. (the throttle body internally regulates the pressure)

    Or optionally, you can retro fit a 87-91 baffled tank from a k5 into your 82, and run a "in tank" fuel pump, but that will require the appropriate fuel lines, (tbi fuel line input and return is 14mm and 16mm)

    Hopefully that's some semi-useful information.
     
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  14. seniorbear69

    seniorbear69 Junior Member

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    HI sorry how do i pm you ?
     
  15. Vbb199

    Vbb199 B-rate Hillbilly Customs Supporting Member

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    Ill send you a message now, or you can text me at 704-738-8300
     

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